An in-wheel vehicle drive motor incorporated in each of a plurality of wheels of a vehicle for directly driving the wheels in a rotatable manner is disclosed in Japanese Laid-Open Patent Publication (JP-A) Nos. 2004-120909 and 2004-120910, for example. Such an electric motor is referred to as an “in-wheel motor.”
Each of the in-wheel motors described in the two above-noted patent documents comprises a motor housing, a rotor that is rotatably supported inside the motor housing and that is connected to the vehicle driving wheels, and a stator in which numerous stator coils are disposed in the order of U-, V-, and W-phases inside the motor housing on the external peripheral side of the rotor. The stator coils are electrically connected to a controller disposed outside of the motor housing, and are energized by the controller in accordance with the rotation angle of the rotor in each phase.
The invention disclosed in JP 2004-120909 A reduces manufacturing costs and achieves a smaller size in the width direction of the vehicle in an in-wheel motor having the above-described configuration by providing a holder for electrically assembling the stator coils in prescribed locations in the housing without the use of a wire connection unit. The invention disclosed in JP 2004-120910 A reduces manufacturing costs and achieves a smaller size in the width direction of the vehicle in the same manner described above in an in-wheel motor having the above-described configuration by providing a terminal board whereby the wiring from the stator coil is electrically consolidated for each phase without the use of a wire connection unit.
In an in-wheel motor that is incorporated in a wheel as described above for directly-driving the wheel in a rotatable manner, a power supply structure cannot be easily incorporated because the structure must be compactly built into a narrow space and because the structure is used in harsh or severe environments that experience vibrations, muddy water, and the like. Such a power supply system is not disclosed for the in-wheel motors described in the two above-described patent documents.
The problem related to the power supply system is not limited to the in-wheel motors described above, but also applies to motors in general.
Therefore, in view of the above-described problem, there is a need for an electric motor that can be compactly incorporated into a narrow space, is highly durable even in very severe environments, has a power supply system capable of achieving high power-supplying performance, and allows omission as many as possible of structural parts of the power supply system including support structures, electric wires, and other components.